1. Field of the Invention
The present invention relates to an object, a method, a production method, a process, a machine, a manufacture, and a composition (a composition of matter). In particular, the present invention relates to a semiconductor device, a display device, a light-emitting device, an electronic device, a driving method thereof, or a manufacturing method thereof. In particular, the present invention relates to a semiconductor device, a display device, an electronic device or a light-emitting device each including an oxide semiconductor.
Note that the term “display device” means a device including a display element. In addition, the display device also includes a driver circuit for driving a plurality of pixels, and the like. Further, the display device includes a control circuit, a power supply circuit, a signal generation circuit, or the like formed over another substrate.
2. Description of the Related Art
For display devices typified by liquid crystal display devices, elements and wirings have been downsized with recent technological innovation and mass production technology has also been improved greatly. Improvement in fabrication yield is required to achieve lower cost in the future.
If a surge voltage due to static electricity or the like is applied to a display device, an element is broken to produce abnormal display. Thus, fabrication yield might be decreased. To overcome that, a protection circuit for releasing a surge voltage to another wiring is provided in a display device (see Patent Documents 1 to 7, for example).
[Reference]
    [Patent Document 1] Japanese Published Patent Application No. 2010-92036    [Patent Document 2] Japanese Published Patent Application No. 2010-92037    [Patent Document 3] Japanese Published Patent Application No. 2010-97203    [Patent Document 4] Japanese Published Patent Application No. 2010-97204    [Patent Document 5] Japanese Published Patent Application No. 2010-107976    [Patent Document 6] Japanese Published Patent Application No. 2010-107977    [Patent Document 7] Japanese Published Patent Application No. 2010-113346